Fixed en passant detection bug

hrushikeshrv · Jan 16, 2023 · 9cadf7d · 9cadf7d
1 parent 80bde5f
commit 9cadf7d
Showing 1 changed file with 14 additions and 15 deletions.
diff --git a/chessengine/bitboard.py b/chessengine/bitboard.py
@@ -42,7 +42,7 @@
     coords_to_pos,
     pos_to_coords,
     san_piece_map,
-    piece_square_table
+    piece_square_table,
 )
 from chessengine.utils import (
     get_bit_positions,
@@ -233,23 +233,23 @@ def score(self):
         """
         s = 0
         piece_values = {
-            'pawns': 100,
-            'rooks': 500,
-            'knights': 320,
-            'bishops': 330,
-            'queens': 900,
-            'kings': 20000
+            "pawns": 100,
+            "rooks": 500,
+            "knights": 320,
+            "bishops": 330,
+            "queens": 900,
+            "kings": 20000,
         }
         for i in range(64):
-            pos = 2 ** i
+            pos = 2**i
             side, piece, _ = self.identify_piece_at(pos)
             if side is None:
                 continue
-            elif side == 'white':
+            elif side == "white":
                 s += piece_values[piece] + piece_square_table[(side, piece)][i]
             else:
                 s -= piece_values[piece] + piece_square_table[(side, piece)][i]
-        if self.side == 'white':
+        if self.side == "white":
             return s
         return -s
 
@@ -494,11 +494,11 @@ def move(self, start: int, end: int, track: bool = True) -> None:
         if start_piece == "pawns":
             if start_side == "white":
                 # Check en passant status
-                if get_rank(end) - get_rank(start) == 2:
+                if get_rank(start) == 2 and get_rank(end) == 4:
                     self.en_passant_position = start << 8
 
                 # Check if a pawn captured by an en passant move
-                elif get_file(start) != get_file(end):
+                elif end == self.en_passant_position:
                     # White pawn made an en passant move
                     black_pawn_bb = self.get_bitboard("black", "pawns")
                     black_pawn_bb &= clear_position[end >> 8]
@@ -512,11 +512,11 @@ def move(self, start: int, end: int, track: bool = True) -> None:
 
             else:
                 # Check en passant status
-                if get_rank(start) - get_rank(end) == 2:
+                if get_rank(start) == 7 and get_rank(end) == 5:
                     self.en_passant_position = start >> 8
 
                 # Check if a pawn captured by an en passant move
-                elif get_file(start) != get_file(end):
+                elif end == self.en_passant_position:
                     # Black pawn made an en passant move
                     white_pawn_bb = self.get_bitboard("white", "pawns")
                     white_pawn_bb &= clear_position[end << 8]
@@ -775,7 +775,6 @@ def get_moves(
                     ("black", "knights"): get_black_knight_moves,
                     ("black", "pawns"): get_black_pawn_moves,
                 }
-                # TODO - Add support for en passant move detection
                 return move_gens[(side, piece)](self, position)
         else:
             moves = []